1. Field of the Invention
The present invention generally relates to spacer clips for thermal insulation and particularly to clips for spacing and supporting stacks of reflective insulation along an edge of the stack.
2. Description of the Prior Art
Reflective insulation is used to encase the main body and associated piping of nuclear reactors to minimize heat and radiation loss therefrom. Reflective insulation is formed in spaced stacks having a plurality of thin Aluminum or Stainless Steel sheets. These spaced sheets are then encased between thicker and more structurally sound inner and outer cases. The encased stacks are custom formed to the contours of the reactor and associated piping and hence require the joining together of variously contoured encased stacks of reflective insulation of various sizes around the reactor. Understandably, these operations involve a great deal of handling. This handling occurs not only during the encasing of the stack in the inner and outer cases but also during the fitting and joining of the encased stacks to the reactor. Since the heat insulating ability of the stacks depends upon minimizing heat transfer by maintaining the spaced zones between the reflective sheets any compression of the stacks will press the individual sheets together and allow conductive heat transfer between the spaced zones impairing the insulating efficiency of the stack. Such compression usually occurs along an edge of the stack when assemblers grab the stack by the end and squeeze together the thin sheets of reflective insulation. Thus a strong spacing clip is required to maintain the structural integrity of the stack during the various handling and assembly operations. The clip also has to support the edge of the stack to prevent the shifting of individual sheets within the stack.
Known clips for maintaining such structural integrity and support include toothed sheet metal strips which are inserted through aligned longitudinal holes in the individual sheets of reflective insulation. The tooth parts of the known clips are formed at right angles to the strip to maintain a spacing between the individual sheets of the stack through line contact with individual sheets. These clips have certain disadvantages. The number of such clips which may be used is limited by the number of preformed slots in the individual sheets. Thus when a particularly difficult contour of the stack requires more support, such support can not be easily provided by merely adding more support clips. Also before the clips can be inserted through the stack, individual sheets of the stack must be aligned to have their slots adjacent each other. Then the individual sheets have to be retained while the clip is threaded through the slots and the tooth members are bent into the space between each sheet. The foregoing steps make the assembly of the stack a difficult and expensive operation.